A chilly northeast wind whipped up whitecaps on New Hampshire's Piscataqua River, as the newly commissioned fleet submarine Squalus, with a crew of 51, five officers and three civilian observers, headed for the open Atlantic and sea trials on May 23, 1939.
Under the command of Lt. Oliver F. Naquin, a 1925 Annapolis graduate, the Squalus, named for a small shark, was preparing for its 19th dive five miles southeast of the Isles of Shoals off Portsmouth, N.H.
"We called it the 'Secretary of the Navy' dive because he stipulated that we had to get down to periscope depth -- that was about 60 feet -- in 60 seconds while going ahead at 16 knots," said Naquin, who later retired as a rear admiral, in a 1986 interview with Smithsonian Magazine.
"If we could dive that fast in wartime, we'd have a good chance of getting under before a patrol plane spotted us. We'd come within two seconds of it on the 18th dive," he said.
After giving the order to "Rig for diving" and then "Stand by to dive," Naquin left the bridge atop the conning tower and went below as klaxons echoed throughout the sub.
The sub was now running on electric motors after its diesel engines had been switched off. Red lights on the control board, which indicated open valves, flashed to green, meaning the valves were closed. The last one, a main engine induction valve that brought in fresh air to the diesels below, went from red to green.
Despite the control board indicating that all valves were closed, there was trouble. Suddenly, a yeoman turned to Naquin and said: "Engine rooms are flooding, sir!"
Naquin ordered the main ballast and safety tanks blown.
"We got the bow up, but there was too much weight to get to the surface. We hung on for a moment, then started going down by the stern, taking an angle of 40 degrees. People couldn't keep their footing," he said.
Watertight doors slammed, trapping 26 men in the after compartments. Rushing sea water shorted out batteries, plunging the Squalus into darkness as she settled 243 feet below the surface.
The crew fired smoke rockets and released from the depths a marker buoy containing a telephone, eventually catching the attention of the Squalus' sister sub, the Sculpin.
The trapped men in the doomed Squalus heard the sub's propellers and then her anchor being dropped. Phone contact was momentarily established until a wave snapped the phone line between the two vessels.
As the hours dragged on with carbon dioxide levels rising and coldness creeping throughout the Squalus, her crew remained calm, hoping for a quick rescue.
A rescue flotilla made up of the Navy tugs Wandank and Penacock began dragging for the Squalus and at 7: 30 p.m., nine hours after going to the bottom, the Penacock's grapnel, a small anchor with four or five curved arms, latched onto a section of the sub's deck railing.
The hero of the disaster would be Lt. Cmdr. Charles "Swede" Momsen, whose 9-ton McCann 1959 FILE PHOTO Lt. Cmdr. 'Swede' Momsen Rescue Chamber, which he had designed with Commander Allan McCann, would eventually free the sub's imprisoned crew.
The chamber -- which had only been used in training missions, never in an actual rescue -- owed its birth to experiments that Momsen carried out in the late 1920s in the hulk of a sunken submarine in the Chesapeake Bay.
In fighting Navy brass who thought incorrectly that sunken subs and their crews would always be doomed, Momsen became an expert in the field of diving operations over sunken subs. In recognition of his work, he was presented the Distinguished Service Medal by President Hoover.
The McCann Rescue Chamber, which attached itself to the hatch of the sunken sub, could convey eight men to the surface in a slow two-hour journey. Hours later, Naquin was the 33rd and last survivor aboard the Squalus to step into the chamber and head for the surface.
After breaking the surface twice, only to plunge back to the bottom, salvors finally were rewarded on Sept. 15, when the mud-stained Squalus reached the surface and was towed to Portsmouth Navy Yard.
The bodies of 25 of the 26 victims were recovered. The 26th body was presumed to have floated away through an open hatch.
Rebuilt and recommissioned as the Sailfish, the sub was assigned to the Pacific Theater of operations where she sank seven enemy vessels, including an aircraft carrier.
An official inquiry concluded that the 1939 disaster was caused by the faulty induction valve.
Naquin, who was never again given the command of a submarine, was assigned to surface ships and retired in 1955.
Momsen, a career Navy man, retired in the 1950s.
In Peter Maas' recently published account of the disaster, "The Terrible Hours," he writes that Momsen belongs in "that special pantheon that the nation reserves for its heroes."
Maas recalls Momsen's diary entry after watching the Squalus arise from the depths.
"As I stood there, I thought I saw a trident and a crown rise out of the water, followed by the face of Neptune, clouded in disappointment. He had been cheated of his prize," he wrote.
Today, a portion of the superstructure and deck of the Squalus, mounted in concrete, can be seen at Portsmouth Navy Yard.